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41.
Among 5315 prenatal diagnoses performed for various indications (maternal age, neural tube defect, metabolic diseases, X-linked diseases, pathologic pregnancies) 29 unexpected structural chromosome rearrangements were found in fetal cells. Fourteen were de novo chromosome rearrangements, six unbalanced, and eight balanced. Fifteen were inherited and balanced rearrangements. This high frequency of structural anomalies is discussed. 相似文献
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A. Triantafyllidis I. Leonardos I. Bista I. D. Kyriazis M. Th. Stoumboudi I. Kappas F. Amat T. J. Abatzopoulos 《Marine Biology》2007,152(5):1159-1167
The purpose of this study was to determine the phylogeographic structure of the brackish-hypersaline cyprinodont fish Aphanius fasciatus (Valenciennes, 1821), using sequencing and RFLP analysis of a 1,330 bp mitochondrial DNA segment containing part of the 16S
rRNA gene as well as the genes for tRNA-Leu, NADH subunit 1 and tRNA-Ile. Individuals were collected from 13 different sites
in Greece and Turkey, while seven published A. fasciatus sequences were also included to cover the area of distribution of the species. Pairwise sequence divergence values ranged
from 0 to 4.51%. Congruent phylogenies were recovered with maximum likelihood, maximum parsimony and neighbour-joining methods.
All analyses revealed two main groups. The first group consists of populations from almost all localities that drain into
the Aegean Sea. The second group comprises the remaining population samples, which in some cases seem to consist of population-specific
subgroups. Our results show that vicariant events have predominantly affected the evolution of A. fasciatus, with the Messinian salinity crisis having shaped the present genetic structure of its populations. Additionally, the life-history
traits of the species, which determine a low potential for dispersal, coupled with the typical fragmentation of brackish-hypersaline
water habitats have led to a high degree of isolation of A. fasciatus populations, even at restricted spatial scales. Analysis of the partitioning of the total amount of polymorphism with analyses
of molecular variance (AMOVA) gave a value of F
ST = 84.6%. Potential conservation policies concerning A. fasciatus should also consider the low-genetic variability in the majority of its populations and the presence of fixed haplotypes
in some of them. 相似文献
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47.
Transfer of hexazinone and glyphosate through undisturbed soil columns in soils under Christmas tree cultivation 总被引:3,自引:0,他引:3
Field studies monitoring pesticide pollution in the Morvan region (France) have revealed surface water contamination by some herbicides. The purpose of this study was to investigate in greater detail the transport of two herbicides, used in Christmas tree production in the Morvan, under controlled laboratory conditions. Thus, the leaching of hexazinone (3-cyclohexyl-6-dimethyl-amino-1-methyl-1,3,5-triazine-2,4 (1H,3H) dione) and glyphosate (N-(phosphono-methyl-glycine)) through structured soil columns was studied using one loamy sand and two sandy loams from sites currently under Christmas tree cultivation in the Morvan. The three soils were cultivated sandy brunisol [Sound reference base for soils, D. Baize, M.C. Girard (Coord.), INRA, Versailles, 1998, 322 p] or, according to the FAO [FAO, World reference base for soil resources, ISSS-ISRIC-FAO, FAO, Rome, Italy, 1998], the La Garenne was an arenosol and the two other soils were cambisols. The clay contents of the soils ranged from 86 to 156 g kg(-1) and the organic carbon ranged from 98 to 347 g kg(-1). After 160 mm of simulated rainfall applied over 12 days, 2-11% of the applied hexazinone was recovered in the leachate. The recovery was much higher than that of glyphosate, which was less than 0.01%. The greater mobility of hexazinone might be related to its much lower adsorption coefficient, K(oc), 19-300 l kg(-1), compared with 8.5-10231 l kg(-1) for glyphosate (literature values). Another factor that may explain the higher amounts of hexazinone recovered in the leachates of the three soil columns is its greater persistence (19.7-91 days) relative to that of glyphosate (7.9-14.4 days). The mobility of both herbicides was greater in the soils with higher gravel contents, coarser textures, and lower organic carbon contents. Moreover, glyphosate migration seems negatively correlated not only to soil organic carbon, but also to aluminium and iron contents of soils. This soil column study suggests that at the watershed scale, surface water contamination by hexazinone could occur via the horizontal subsurface flow in upper centimeters of soil. In contrast, the surface water contamination with glyphosate by this mechanism appears unlikely. 相似文献
48.
In an in vivo/in vitro assay system (Massa et al., 1990) we have detected the carcinogenic activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The carcinogenic potential measured in this system is concentration-dependent. Experiments with other carcinogenic compounds have revealed that TCDD at low doses can act as co-carcinogen. At higher concentrations TCDD induces TNF-α production. 相似文献
49.
The toxicity and toxic potential of fly ash were assessed, using rainbow trout yolk sac fry. In contrast to fly ash itself, extracts of fly ash were extremely toxic, producing typical toxicopathological features of TCDD-intoxication. By comparison with earlier experiments using pure 2,3,7,8-TCDD, the toxic potential of fly ash was roughly estimated to be 75–125 ng.g?1 toxic aequivalents TCDD. Obviously, this toxic potential is attributable for a minor part to 2,3,7,8-TCDD and for the greater part to the other chlorinated dioxin congeners and the dibenzofurans, present in fly ash. 相似文献
50.
Der Vergleich der Strahlendosis aus Umwelt, Zivilisation und Medizin besagt, da? jeder dieser drei Bereiche wesentlich zu
der Dosis beitragen kann, die ein Mensch w?hrend seines Lebens erh?lt. Es zeigt sich aber auch, da? es m?glich ist, die Strahlenbelastung
zu reduzieren. So steigt bei erh?hter W?rmed?mmung und der damit verbundenen geringeren Ventilation eines Raumes bei bestimmten
Baustoffen die Radioaktivit?t in diesen R?umen an. Manche Regionen in der Bundesrepublik Deutschland und in der Welt weisen
erhebliche Unterschiede durch terrestrische und kosmische Strahlung auf. Diese Dosis kann bei unterschiedlichen Flugrouten
vermieden werden. Die eingesparten Werte k?nnen, z.B., bezogen auf die Gonadendosis, die Strahlenexposition im Rahmen einer
R?ntgendiagnostik ausgleichen. 相似文献